Why America's Founders, especially the first four Presidents, supported "religion" in general/"Christianity" in particular is much misunderstood. It wasn't because they necessarily personally believed in the doctrinal contents of the specific religions to which they were friendly. It certainly wasn't because "they" (as a collective) were orthodox Christians who believed Christ's Atonement the only way to God. Rather, it was because they supported the sects' teachings on Providence, morality and consequently the civic utility said sects engendered.
The Founders seemingly played the doctrinal differences -- including differences on the Trinity and related orthodox doctrines -- of the different sects against one another to cancel one another out and bring civic peace (see Madison in Federalists 10 and 51 on factions and multiplicity of sects).
As my co-blogger Tom Van Dyke noted, they followed Voltaire's dictum:
If there were only one religion in England, there would be danger of tyranny; if there were two, they would cut each other's throats; but there are thirty, and they live happily together in peace.
That might explain why Jefferson invited John Hargrove (1750-1839) to deliver numerous sermons that PROSELYTIZED for Swedenborgianism to members of Congress. It wasn't because Jefferson believed in the exotic Christology -- that was neither unitarian nor trinitarian -- of the Swedenborgs. Rather, Jefferson wanted to send the message that the Swedenborgs were invited to the ecumenical party of American Founding political-theology, and one's orthodox views on the Trinity simply would not be a criterion -- part of a private, informal religious test, when Art. VI. Cl. 3 of the US Constitution bans formal religious tests.
With that, here Rev. Hargrove preaches Swedenborgianism to both houses of Congress and the President.
This will appear irresistibly evident from the whole tenor of the sacred scriptures, particularly the 50th psalm (which indeed seems a literal extract from the 16th chapter of the first book of Chronicles)—but then, it should be known, that in the Deity, whom we call Jehovah-God, there exists a divine Trinity; not of persons however, but of essential principles, which principles, when rightly apprehended, we have no objection to call Father, Son, and Holy Ghost; or, to speak more intelligibly, the Divine Love, the Divine Wisdom, and the Divine proceeding Power, which trinity also, corresponds unto that, in every individual man, to wit, his will, his understanding, and their proceeding affections and perceptions; hence therefore, it is written that “God created man in his own image and in his own likeness.” [Bold mine.]